Having a fire extinguisher in a caravan as a device to aid getting to the door is not really worth considering.
What type of extinguisher would be appropriate in the confines of a caravan to aid safe egress?,
Water
Co2
Dry Powder
Foam
I have trained in fire extinguisher use and also been a trainer for fire extinguisher use, there are just too many scenarios for the location and type of fire in a caravan .e.g. electrical fire, woodpaperfabric, propanebutane gas and plastics etc.
Keep the route to the door uncluttered, cover yourself with a blanket if necessary (things are already pretty grim if you are in this situation) and just get out, you probably do not have time, nor will be able to get out of a window, they are not designed as a means of escape.
So you get outside safely, now you can consider if it is safe to fight the fire, it may be safe to fight it if you have the appropriate equipment, this could be an extinguisher or fire blanket or the pretty much useless bucket of sand.
Not going to go into it here but your choice of extinguisher may exacerbate the situation, as a reasonable choice for having only one type of extinguisher then dry powder is a good choice, and if you also had a Co2 then you have a good option in the event of an electrical fire.
(I don't know anybody who carries both, if I could carry only one thing then it would be a fire blanket).
And keep the extinguisher outside the caravan where you won't fall over it and it is easy to lay your hands on, you could store it in the sand bucket

.
I hope it never happens to any of you, and if you have not had basic fire fighting training in the use of extinguishers then it is probably best to get far away and raise the alarm.